003 File Manager
Current Path:
/usr/src/lib/librss
usr
/
src
/
lib
/
librss
/
📁
..
📄
Makefile
(150 B)
📄
Makefile.depend
(258 B)
📄
librss.3
(4.13 KB)
📄
librss.c
(6.55 KB)
📄
librss.h
(2.96 KB)
Editing: librss.3
.\" $FreeBSD$ .\" .Dd October 23, 2016 .Dt LIBRSS 3 .Os .Sh NAME .Nm librss .Nd Provide Receive-side scaling awareness to userland applications .Sh LIBRARY .Lb librss .Sh SYNOPSIS .In sys/param.h .In sys/cpuset.h .In librss.h .Ft struct rss_config * .Fn rss_config_get "void" .Ft void .Fn rss_config_free "struct rss_config *cfg" .Ft int .Fn rss_config_get_bucket_count "struct rss_config *cfg" .Ft int .Fn rss_get_bucket_cpuset "struct rss_config *rc" "rss_bucket_type_t btype" "int bucket" "cpuset_t *cs" .Ft int .Fn rss_set_bucket_rebalance_cb "rss_bucket_rebalance_cb_t *cb" "void *cbdata" .Ft int .Fn rss_sock_set_bindmulti "int fd" "int af" "int val" .Ft int .Fn rss_sock_set_rss_bucket "int fd" "int af" "int rss_bucket" .Ft int .Fn rss_sock_set_recvrss "int fd" "int af" "int val" .Sh DESCRIPTION The .Nm library and the functions it provides are used for both fetching the system RSS configuration and interacting with RSS aware sockets. .Pp Applications will typically call .Fn rss_config_get to fetch the current RSS configuration from the system and perform initial setup. This typically involves spawning worker threads, one per RSS bucket, and optionally binding them to the per-bucket CPU set. .Pp The .Vt rss_config struct is defined as: .Bd -literal struct rss_config { int rss_ncpus; int rss_nbuckets; int rss_basecpu; int *rss_bucket_map; }; .Ed .Pp Applications will typically use the .Fn rss_config_get_bucket_count function to fetch the number of RSS buckets, create one thread per RSS bucket for RSS aware work, then one RSS aware socket to receive UDP datagrams or TCP connections in each particular RSS bucket / thread. .Pp The .Fn rss_get_bucket_cpuset function sets the given cpuset up for the given RSS bucket and behaviour. Typically applications will wish to just query for .Vt RSS_BUCKET_TYPE_KERNEL_ALL unless they wish to potentially setup different worker threads for transmit and receive. .Pp The .Vt rss_bucket_type_t enum is defined as: .Bd -literal typedef enum { RSS_BUCKET_TYPE_NONE = 0, RSS_BUCKET_TYPE_KERNEL_ALL = 1, RSS_BUCKET_TYPE_KERNEL_TX = 2, RSS_BUCKET_TYPE_KERNEL_RX = 3, RSS_BUCKET_TYPE_MAX = 3, } rss_bucket_type_t; .Ed .Pp The rebalance callback .Vt rss_bucket_rebalance_cb_t is defined as: .Bd -literal typedef void rss_bucket_rebalance_cb_t(void *arg); .Ed .Pp The .Fn rss_set_bucket_rebalance_cb function sets an optional callback that will be called if the kernel rebalances RSS buckets. This is intended as a future expansion to rebalance buckets rather than reprogram the RSS key, so typically the only work to be performed is to rebind worker threads to an updated cpuset. .Pp Once RSS setup is completed, .Fn rss_config_free is called to free the RSS configuration structure. .Pp To make a .Vt bind socket RSS aware, the .Fn rss_sock_set_bindmulti function is used to enable or disable per-RSS bucket behaviour. The socket filedescriptor, address family and enable flag .Vt val are passed in. .Pp If .Vt val is set to 1, the socket can be placed in an RSS bucket and will only accept datagrams (for UDP) or connections (for TCP) that are received for that RSS bucket. If set to 0, the socket is placed in the default PCB and will see datagrams/connections that are not initially consumed by a PCB aware socket. .Pp The .Fn rss_sock_set_rss_bucket function configures the RSS bucket which a socket belongs in. Note that TCP sockets created by .Xr accept 2 will automatically be assigned to the RSS bucket. .Pp The .Fn rss_sock_set_recvrss function enables or disables receiving RSS related information as socket options in. .2 recvmsg calls. .Pp When enabled, UDP datagrams will have a message with the .Vt IP_RECVFLOWID option indicating the 32-bit receive flowid as a uint32_t, and the .Vt IP_RECVRSSBUCKETID option indicating the 32 bit RSS bucket id as a uint32_t. .Sh ERRORS The functions return either <0 or NULL as appropriate upon error. .Sh SEE ALSO .Xr PCBGROUP 9 .Sh HISTORY The .Xr librss.3 library first appeared in .Fx 11.0 . .Sh AUTHORS .An Adrian Chadd Aq Mt adrian@FreeBSD.org .Sh BUGS There is currently no kernel mechanism to rebalance the RSS bucket to CPU mapping, and so the callback mechanism is a no-op.
Upload File
Create Folder